configure: add a proper configure script

It's not very good, but it supports all of the options by the
previous far-worse Makefile configure targets, and also now supports
out-of-tree builds.

Also include the relevent updates to the .buildbot script and
.gitignore.

configure

@@ -0,0 +1,74 @@
+#!/bin/bash
+
+CONFIG_MAK=config.mak
+MAKEFILE=Makefile
+
+debug="no"
+coverage="no"
+release="no"
+output_dir=$(pwd)
+proj_dir=$(dirname "$BASH_SOURCE")
+
+for arg in $@; do
+    case $arg in
+	--debug)
+	    debug="yes"
+	;;
+	--release)
+	    release="yes"
+	;;
+	--coverage)
+	    coverage="yes"
+	;;
+	*)
+	    echo "unknown option $arg"
+	    exit 1
+    esac
+done
+
+add_define()
+{
+    var=$1
+    shift
+
+    if [[ $# -gt 0 ]]; then
+	echo "$var=$@" >> $CONFIG_MAK
+    else
+	echo "# $var is not defined" >> CONFIG_MAK
+    fi
+
+}
+
+quiet()
+{
+    $@ 2> /dev/null 1> /dev/null
+}
+
+quiet rm $CONFIG_MAK
+
+if [[ ! -e $MAKEFILE ]]; then
+    quiet ln -s $proj_dir/$MAKEFILE $MAKEFILE
+fi
+
+ccflags_extra=""
+ldflags_extra=""
+
+if [[ "$debug" == "yes" ]]; then
+    ccflags_extra="$ccflags_extra -DLOG_LEVEL=5 -DDEBUG -O0 -ggdb"
+fi
+
+if [[ "$coverage" == "yes" ]]; then
+   ccflags_extra="$ccflags_extra --coverage -fprofile-arcs -ftest-coverage"
+   ldflags_extra="$ldflags_extra -lgcov --coverage"
+fi
+
+if [[ "$release" == "yes" ]]; then
+    ccflags_extra="$ccflags_extra -O3"
+fi
+
+add_define CCFLAGS_EXTRA "$ccflags_extra"
+add_define LDFLAGS_EXTRA "$ldflags_extra"
+add_define OUT "$output_dir"
+add_define SRC_DIR "$proj_dir/src"
+
+exit 0